Sound amplifying device



March 1933- c. N. ANDREWS SOUND AMFLIFYING DEVICE Filed March 5, 1-928 Patented Mar. 7, 1933 CYRTJ S N. ANDREWS, OF YUCAIPA, CALIFORNIA SOUND Ali'IPLIFYING DEVICE Application filed March 3, 1928.

This invention relates to sound amplifying devices in radio speaking apparatus.

Heretofore it has been common practice in the construction of sound amplifying devices 5 to employ an electric vibrator and a diaphragm actuated by said vibrator to amplify sound in those mechanisms whichuse'electrical energy as a carrying medium. In the type of devices mentioned above, the diaphragm vibrates directly into the surrounding atmosphere and the sound that is heard is the result of such vibration. Many attempts have been made to modulate the tone and quality of sound in loudspeakers such at- ]5: tempts have met with various degreesof success short of perfection and in spite of all endeavor the present day loud speaker is not satisfactory for the reason that itdoes not perfectly reproduce sound of all wavelengths and there results a distortion of soundand in many cases a blasting sound is produced which is not only distracting but is highly objectionable to listeners.

Therefore an object of my invention is to provide a sound amplifying device that improves tone modulation.-

Another object is to provide a device that is capable of sound amplification without creating any blasting or other disturbing or 0 disagreeable sounds. v 1 A feature of my'invention is the correlation of an electrically operated vibrator and a diaphragm and the sounding board of a musical instrument for the reproduction of sound. 7

An advantage of my invention in sound reproduction is the complete elimination of tinny sounds, such as-usually accompanies sound amplification.

4 An advantage of my invention is, that it is possible through its reproduction of orchestral music to hear more of the instruments playing in the orchestra and with their tone values better preserved than ispossible with 5 former devices known 'to me; the foregoing statement is also true'of vocal music, in that the tone valve is not distorted in the reproduction but is preserved and is given to the listening audience of the reproduction, as truly and as clearly as if the source of the en Serial No. 258,889.

Fzmclamentals and harmonics In the reproduction of music and speech the great desideratum to be obtained is not only the reproduction of the fundamentaltones but also the reproduction of their harmonics with fidelity, true tonal quality and modulation. These results, I claim to have obtained.

New type of sound diaphragm After several years of experiments and results I discovered that if my new type of sound diaphragm be clamped at its periphery to a sounding board and said diaphragm be 5 pulsated, said pulsations would radiate through its perimeter into the sounding board, be harmonized, amplified and radiated by said sounding board with fidelity, true tonal qualities and modulation. Y

The construction of the present types of loud speakers does not permit the radial harmonics to be utilized but such harmonics are nullified at the perimeter of the diaphragms to'th'e great loss of the tonal qualities in sound reproduction.

. Radial 8mm diaphragm By means of my new type of sound diaphragm which 1 term my radial sound diaphragin, I have discovered and utilized four I term the second fundamental. The third motion of the diaphragm I term the first harmonics, the resultant of the first fundamental that radiates through the perimeter and the rings into the sounding board. The fourth motion of the diaphragm 1 term the second harmonics the resultant of the second fundamental that'also radiates through the perimeter and the rings into the sounding board.

Other objects, advantages and features of invention may appear from the accompanying drawing, the subjoine-d detailed description and the appended claims.

The accompanying drawing illustrates the invention.

Fig. 1 is a broken elevation partly in longitudinal section through the center of the acoustic diaphragm and through the sound board, and through the housing, and showing 1111 unbroken side elevation, a conventional form of electro-magnetic resonator and vibration transmitting pin connecting the resonator, and diaphragm.

Fig. 2 is a view of the portion of Fig. 1 WliZl1lI1 the circle the diaphragm rim and viewed from line a22:v2, looking left in the direction indicated by the sight arrows on said line;

1 generally indicates a well known electro- 9' magnetic vibration amplifier, 2 a circular radialdiaphragm, and 3 the sound board or resonator, shown as a fragment of the sound board of an upright piano.

It is understood that said resonator may =be of any form, shape and dimensions within the approval of the constructor skilled in resonant acoustics.

The diaphragm 2 is preferably circular and its circular rim is preferably clamped by an annular plate or ring 6, upon a lift 7 that forms resonant connection between the diaphragm and the body of the extended resonator 3.

The clamping member 6 and the diav-f phragm seat 7 holdthe diaphragm vibrationally free from the sound board within the bounds of the lift 7, and screws 8 are shown extending through the clamp ring 6, and into the sound board to hold the rim of the diaphragm in positive resonant connection with the resonator, and providing a clearance space or resonating chamber 9 extending throughout the space enclosed within the lift between the diaphragm 2 and the resonator 3.

The electric vibrator 10 with its magnets 11 and 12 operates the drive pin 14 and the end of said pin opposite said magnets is inserted through the center of the diaphragm and positively connected therewith so that the space 9 is closed to the external air and forms an acoustic chamber between the diaphragm 2 and'the resonator 3.

In order that the sounding board may be in sympathetic as well as direct mechanical vibration with the vibration of the diaphragm it may be desirable to change the capacity of the space 9, this may be accomplished by varying the thickness of the lift or ring 7, or the diameter of the diaphragm 2, or by changing both the dimensions of the foregoing features.

The pin 14 is connected to the diaphragm 2 so that as the vibration of the electric vibrator vibrates due to incoming electrical im pulses the diaphragm will also vibrate; and as it does so, sound Waves will be set up in the resonating chamber or clearance space 9, and in turn the sound wave vibration will be imparted to the sounding board of the instrument forming a resonator to which sounding board the radial diaphragm itattached and will be in sympathetic vibration as well as direct mechanical Vibration with said diaphragm, thus modulating and clarifying the tone value of incoming music or other sound.

As shown in Fig. l, 15 is a housing for the electric vibrator, and is adapted to be adj ustably positioned by means of a standard 16 over which bands 17 fixed to the housing 15 are placed. Set screws 18 through said bands engage the standard 16 and hold the housing in a predetermined position.

The standard 16' has a footing 19 resting upon a base 20 and is secured thereto by means of screws 21.

The electro-magnetically operated vibrator with its pin 1 cooperate with the diaphragm 2 to vibrate such diaphragm, responsive to the impulses of the vibrator, set up by radio action; the pin 1d being thus actuated electromagnetically, vibrates the diaphragm, and the vibrations of such diaphragm are not bounded by or limited to the periphery of the diaphragm, but extend radially from the center of the diaphragm through the ring 7 to the wooden sounding board 3 and thence radially to set up vibrations in such sounding board which extends considerably beyondthe periphery of the diaphragm, as with the sounding board of a piano. In the drawing, said sounding board and piano constructions are broken to indicate that said board may extend indefinitely within the judgement of the constructor.

In the operation of the loud speaker it will be apparent that upon energizin of the magnets 11 and 12 the armature will uetuate and transmit its pulsations or vibrations to the connecting pin 14 which transmits the vibrations to the center of the diaphra m. The vibrations pass radially of the iaphragm to every point adjacent its periphery between the rings 6 and 7 and through the latter to the relatively large sounding board or resonator 3 from which the sound vibrations emanate to the at mosphere. As previously pointed out, the

closed air space confined between the diaphragm 2 and the resonator 3 may be adjusted to facilitate the control of the modulation of the sound waves transmitted to the resonator 3 and emanating therefrom. At any Y rate for improved modulation of the sound waves coming from pin 14, the area of the resonator should be of a greater dimension than the periphery of the-diaphragm confined between the annular members 6 and '7. 1

It is noted that by the provision of a sound board resonator it is made possible to emanate sound from a. motion picture screen as the area of the resonator is such that it is adapted to that purpose, thus to serve a double purpose of modulated sound delivery and light reflection and by its use the voicing of the characters is made highly realistic since the tones coming directly from the screen impress the audience as emanating directly from the actor that attracts the eye as the speaker.

An object of this invention is to make provision for reproducing with fidelity widely variant sounds.

The voice of a man is naturally heavier, vibrating at between and 300 vibrations per second, while a womans voice goes up to 500 and 700 vibrations. At this vibration the sibilant sounds, such as S, Z and the hard 0, X and P become hisses or blasts.

,By translating sounds radially as by my newly invented radial diaphragm arrangement I have provided a practical sound amplifying device, that rectifies those distortions to a very great extent and reduces the distortions of blasting produced by too loud singing or too much volume in orchestral or band music.

The radial diaphragm radiates the vibrations from the center to the perimeter, is then conveyed through the plates to sounding board and amplified by the sounding board.

Radial power emit The combinations of my radial sound diaphragms and power units of the electrodynamic type and the electro-magnetic type constitute my radial power units.

In order to obtain the best results the electro-dynamic radial power units should be used in the lower tone register of the sound board and the electro-magnetic radial units should be used in the upper tone register of the sound board.

Special attention should be given in selection of material used, size, form, thickness and function of the diaphragm.

Radial sounding board The combination of my radial power units and my radial sounding board. constitutes my sound amplifying device. In order to obtain the best results the material used, method of construction, thickness and thinness of definite portions, form, size and function of the radial sounding board should be specially considered.

The variety, tone and volume of the sound amplifier may be greatly improved by the combination of my several radial units clamped to the sound board and operated in an electric circuit.

Reproduction and amplification This building up system of sound reproduction and amplification is an entirely new art and diametrically opposite to the present method of sound reproduction and amplification whereby loud speakers are used and an attempt is made to reduce the discordant sounds by means of bafiie boards or similar devices.

The discovery and use of four superposed motions of a sound diaphragm and their resultant supertones instead of only two motions of diaphragm heretofore known, are to me, great improvements in the art of sound reproduction and amplification.

I claim 1. The combination with a sounding board and a drive pin; of a diaphragm centrally spaced from and fixed around its rim, to the sound board, and centrally connected to the drive pin to vibrate withthe same. 7'

2. In a loud speaker comprising a sounding board, a diaphragm, and drive pin forimparting sound waves to the diaphragm, a sound wave distributing chamber closed to the external air and interposed between the sound wave imparting diaphragm and the sounding board for the purpose of modulating the sound wave action upon the sounding board.

'3. In a sound amplifying device, a diaphragm, a sounding board, resonant means to secure the rim of the diaphragm to the body of the sounding board and means to actuate said diaphragm for the reproduction of sound; said diaphragm being free from the sounding board except at its rim; there being a resonant air chamber between the diaphragm and sounding board.

4. In a sound amplifying device, a'sounding board, a diaphragm means to secure the rim of said diaphragm air tight to the sounding board; a drive pin connecting said diaphragm with an actuating mechanism for the reproduction of sound; there being an acoustic chamber between the diaphragm and sound board.

5. In a sound amplifying device, the combination of a diaphragm and a sounding board spaced apart, and lying in junta-positioned parallel planes, said diaphragm and said sounding board being adapted and arranged to form a closed acoustic chamber to co-ordinate vibration of the diaphragm and sound.

351 waves thereto; a sounding board secured to 7. In a sound amplifying device, a diaphragm, an instrument sounding board. means relating the rim of said diaphragm with said sounding board and means to vibrate said diaphragm for the reproduction of sound; the diaphragm being free from the sounding board except at the rim of the dia phragm.

8. In a sound amplifying device, a diaphragm, a sounding board, means acoustically relating the rim of said diaphragm to said sounding board, and means to vibrate said diaphragm and said sounding board for the reproduction of sound; there being a closed resonant air chamber between the diaphragm and sounding board for the acoustic operation of the sounding board.

9. A sound amplifying device comprising a vibrator, a diaphragm, means connecting said vibrator and said diaphragm, a sounding board, rings on opposite sides of said diaphragm for spacing said diaphragm from said sounding board and means for securing said rings and diaphragm to said sounding board, a housing for said vibrator and a standard to provide adjustment of said housing relative to said diaphragm.

10. In a loud speaker embodying a diaphragm and means for imparting sound said diaphragm forming a resonator, and means for driving and transmitting said sound waves radially of said diaphragm; there being between the diaphragm and the sounding board, an air chamber closed to the atmosphere.

11. In a loud speaker comprising a diaphragm, the combination with means for transmitting sound waves radially through said diaphragm of a sounding board joining said diaphragm forming therewith, a closed resonator chamber for modulating the sound.

12. In a loud speaker comprising a diaphragm for transmitting vibrations radially thereof, and a resonator having a relatively greater emanating area than the diaphragm and secured thereto in spaced relation.

13. The combination with a wooden sounding board, of a diaphragm; a sound wave conducting ring between the rim of the diaphragm and the sounding board, and means, including screws extending through the diaphragm and the ring and holding the diaphragm, ring and sounding board together as an integral sound wave conducting unit; said sounding board having considerable extension beyond the periphery of the dia' phragm and a vibrator pin arranged to vibrate the diaphragm.

14. The combination with a wooden sounding board; of a diaphragm, the rim of which is connected to the sounding board to transmit vibrations thereto, the center of the diaphragm being free from the sounding board; and means to set up sound wave vibrations in the center of the diaphragm and to cause said waves to radiate from said center to the sounding board and therein radially beyond the rim of the diaphragm.

In testimony whereof, I have hereunto set my hand at Los Angeles, California, this 24th day of February, 1928.

CYRUS N. ANDREWS. 

